Changing value of shapekeys keyblocks with a specific name for all objects inside a Blender collection
Get the collection by its name and loop over mesh objects (or others that have shape keys) in it to reach their shape keys.

import bpy

collection_name = "Collection"

collection = bpy.data.collections.get( collection_name )

if collection:
    for obj in [o for o in collection.objects if o.type == 'MESH']:
        key_block = obj.data.shape_keys.key_blocks.get( "Opened" )
        if key_block:
            key_block.value = 0